`propagation_setup`¶

This module contains submodules to define settings for the numerical propagation of states of natural and artificail bodies. A detailed overview of the propagation framework in Tudat can be found in the user guide .

As a short overview of how the submodules below are used in the context of a propagation:

Defining state derivative model settings for propagation of translational, rotational and mass dynamics: acceleration, torque and mass_rate, with thrust-specific models in thrust
Defining settings for the numerical integration: integrator
Defining settings for saving additional (dependent) variables in addition to the state variables: dependent_variable
Combining settings into a full propagation settings: propagator

More details on the procedure and options in creating environment models and bodies can be found in our user guide. For the use of the environment models during a numerical propagation (for instance for custom models) see here.

Functions¶

`create_acceleration_models`(body_system, ...)	Function to create a set of acceleration models from a dictionary of bodies linked to acceleration model types.
`create_torque_models`(body_system, ...)	Function to create a set of acceleration models from a dictionary of bodies linked to acceleration model types.
`create_mass_rate_models`(body_system, ...)	Function to create a set of mass-rate models from associated settings.

create_acceleration_models(body_system: tudatpy.kernel.dynamics.environment.SystemOfBodies, selected_acceleration_per_body: dict[str, dict[str, list[tudatpy.kernel.dynamics.propagation_setup.acceleration.AccelerationSettings]]], bodies_to_propagate: list[str], central_bodies: list[str]) → dict[str, dict[str, list[tudat::basic_astrodynamics::AccelerationModel<Eigen::Matrix<double, 3, 1, 0, 3, 1> >]]]¶

Function to create a set of acceleration models from a dictionary of bodies linked to acceleration model types.

Function to create a set of acceleration models from a map of bodies and acceleration model types. The propagated bodies and central bodies are provided as two separate lists with the same order.

Parameters:

body_system (SystemOfBodies) – System of bodies to be used in the propagation.
selected_acceleration_per_body (Dict[str, Dict[str, List[AccelerationSettings]]]) – Key-value container, with key denoting the body undergoing the acceleration, and the value containing an additional key-value container, with the body exerting acceleration, and list of acceleration settings exerted by this body.
bodies_to_propagate (list) – List of bodies to propagate.
central_bodies (list) – List of central bodies, each referred to each propagated body in the same order.

Returns:

AccelerationMap – Set of accelerations acting on the bodies to propagate, provided as dual key-value container (dictionary), similar to the acceleration settings input, but now with AccelerationModel lists as inner value

Return type:

dict[str, list[AccelerationModel]]

Examples

In this example, the acceleration model includes a spherical harmonic (degree and order 5) gravitational acceleration and aerodynamic acceleration exerted by the Earth, as well as point-mass gravity exerted by the Sun and the Moon. The variable accelerations_settings_vehicle denotes the list of bodies exerting accelerations and the types of accelerations, while the variable acceleration_settings associates this list with the body undergoing the acceleration ("Vehicle").

# Define bodies that are propagated.
bodies_to_propagate = ["Vehicle"]

# Define central bodies.
central_bodies = ["Earth"]

# Define accelerations acting on Vehicle
accelerations_settings_vehicle = dict(
    Sun=[propagation_setup.acceleration.point_mass_gravity()],
    Moon=[propagation_setup.acceleration.point_mass_gravity()],
    Earth=[propagation_setup.acceleration.spherical_harmonic_gravity(5, 5),
           propagation_setup.acceleration.aerodynamic()]
)

# Create global accelerations settings dictionary
acceleration_settings = {"Vehicle": accelerations_settings_vehicle}

# Create acceleration models
acceleration_models = propagation_setup.create_acceleration_models(
    bodies, acceleration_settings,  bodies_to_propagate, central_bodies)

create_torque_models(body_system: tudatpy.kernel.dynamics.environment.SystemOfBodies, selected_torque_per_body: dict[str, dict[str, list[tudatpy.kernel.dynamics.propagation_setup.torque.TorqueSettings]]], bodies_to_propagate: list[str]) → dict[str, dict[str, list[tudat::basic_astrodynamics::TorqueModel]]]¶

Function to create a set of acceleration models from a dictionary of bodies linked to acceleration model types.

Function to create a set of acceleration models from a map of bodies and acceleration model types. The propagated bodies is provided as a list.

Parameters:

body_system (SystemOfBodies) – System of bodies to be used in the propagation.
selected_torque_per_body (Dict[str, Dict[str, List[TorqueSettings]]]) – Key-value container, with key denoting the body undergoing the torque, and the value containing an additional key-value container, with the body exerting torque, and list of torque settings exerted by this body.
bodies_to_propagate (list) – List of bodies to propagate.

Returns:

Set of torques acting on the bodies to propagate, provided as dual key-value container, similar to the torque settings input, but now with TorqueModel lists as inner value

Return type:

TorqueModelMap

Examples

In this example, the following torques are exerted on the vehicle: spherical-harmonic gravitational torque (up to order 4 and degree 4) and aerodynamic torque exerted by the Earth, second-degree gravitational torque exerted by the Sun and the Moon. The variable torques_settings_vehicle denotes the list of bodies exerting torques and the types of torques, while the variable torque_settings associates this list with the body undergoing the torque.

# Define bodies that are propagated
bodies_to_propagate = ["Vehicle"]

# Define torques per each exerting body
torque_settings_vehicle = dict(
    Sun=[propagation_setup.torque.second_degree_gravitational()],
    Moon=[propagation_setup.torque.second_degree_gravitational()],
    Earth=[propagation_setup.torque.spherical_harmonic_gravitational(4, 4),
           propagation_setup.torque.aerodynamic()]
)

# Create global torque settings dictionary
torque_settings = {"Vehicle": torque_settings_vehicle}

# Create torque models
torque_models = propagation_setup.create_torque_models(
    bodies, torque_settings,  bodies_to_propagate )

create_mass_rate_models(body_system: tudatpy.kernel.dynamics.environment.SystemOfBodies, selected_mass_rates_per_body: dict[str, list[tudatpy.kernel.dynamics.propagation_setup.mass_rate.MassRateModelSettings]], acceleration_models: dict[str, dict[str, list[tudat::basic_astrodynamics::AccelerationModel<Eigen::Matrix<double, 3, 1, 0, 3, 1> >]]] = None) → dict[str, list[tudat::basic_astrodynamics::MassRateModel]]¶

Function to create a set of mass-rate models from associated settings.

Function to create a set of mass-rate models from a map of bodies and mass-rate model types. If the mass-rate depends on any acceleration models (e.g. thrust), the acceleration models must be provided as an input.

Parameters:

body_system (SystemOfBodies) – System of bodies to be used in the propagation.
selected_mass_rates_per_body (Dict[str, List[MassRateModelSettings]]) – Key-value container, with key denoting the body with changing mass, and the value containing a list of mass rate settings (in most cases, this list will have only a single entry)
acceleration_models (dict[str, list[AccelerationModel]]) – Sorted list of acceleration models, as created by create_acceleration_models()

Returns:

Set of mass-rate models, as key-value container, same as the settings input, with the difference that the rate settings objects have been processed into the associated objects calculating the actual mass-rate changes.

Return type:

MassRateModelMap

propagation_setup¶

Functions¶

`propagation_setup`¶